Abstract: To investigate the causative agent of exudative epidermitis in 7?day?old suckling piglets on a large? scale pig farm in Jiangmen，Guangdong Province in April 2026，skin scabs and exudates from affected piglets were collected. The isolate was subjected to systematic identification，including isolation and culture，morphological observation，biochemical identification，16S rRNA and gap gene sequencing，and antimicrobial susceptibility testing. The carriage of six exfoliative toxin genes（ExhA，ExhB，ExhC，ExhD，ShetA，ShetB）was also examined. The results showed that the isolate exhibited no hemolysis on blood agar plates，appeared as Gram positive cocci arranged in typical grape like clusters under microscopic examination，and displayed biochemical characteristics consistent with Staphylococcus hyicus. Sequence analysis of the 16S rRNA and gap genes revealed that the isolate shared 100.0% identity with reference strains of Staphylococcus hyicus，and 95.3%–97.0% identity with other staphylococci，such as Staphylococcus aureus；notably，the gap gene exhibited 99.9%–100.0% identity with representative Staphylococcus hyicus strains of both porcine and human origin. Based on these results，the isolate was preliminarily identified as Staphylococcus hyicus and designated strain GDjm 202604. Antimicrobial susceptibility testing showed that the isolate was susceptible to 11 agents， including cefazolin， ceftriaxone， enrofloxacin， novobiocin， and gentamicin； intermediately susceptible to amoxicillin，neomycin sulfate，and ampicillin sulbactam；and resistant to 12 agents， including ampicillin，lincomycin，doxycycline，and trimethoprim. Detection of exfoliative toxin genes revealed that only ExhC was positive，while the other five were negative；the ExhC gene sequence shared 100.0% identity with a strain isolated from Zhaoqing and 99.0%–99.8% identity with other domestic and international strains，indicating that ExhC exfoliative toxin is the major virulence factor of this strain. This study provides reference data for the etiological diagnosis，rational clinical antimicrobial use，and integrated prevention and control of exudative dermatitis in piglets in the Guangdong Province.

Key words: Staphylococcus hyicus；Isolation and identification；exfoliative toxin；Drug sensitivity test

摘要： 为探究2026年4月广东江门某规模化猪场7日龄哺乳仔猪渗出性皮炎的病原菌，该 研究采集发病仔猪皮肤痂皮及渗出液，通过平板划线分离培养、形态学观察、生化特征鉴定、 16S rRNA 及gap 基因测序和药物敏感性试验进行系统鉴定，并进一步检测分离菌株是否携带6 种表皮脱落毒素基因（ExhA、ExhB、ExhC、ExhD、ShetA、ShetB）。结果显示，分离菌株在血平板上 无溶血现象，镜检呈典型葡萄串状排列，为革兰阳性球菌，生化特征与猪葡萄球菌相符。16S rRNA 和gap 基因序列分析表明，该菌株与国外分离的猪葡萄球菌代表株同源性达100.0%，与 其他葡萄球菌（如金黄色葡萄球菌）的同源性为95.3%－97.0%；其中gap 基因与来源于猪和人的 猪葡萄球菌代表株同源性为99.9%－100.0%。将该菌株初步鉴定为猪葡萄球菌（Staphylococcus hyicus），命名为GDjm?202604株。药敏试验结果显示，分离株对头孢唑啉、头孢曲松、恩诺沙 星、新生霉素和庆大霉素等11种药物敏感，对阿莫西林、硫酸新霉素和氨苄西林?舒巴坦3种药 物中介敏感，对氨苄西林、林可霉素、强力霉素和甲氧苄啶等12种药物耐药。表皮脱落毒素基 因检测结果显示，该菌株ExhC 基因为阳性，其余5种毒素基因均为阴性；ExhC 基因测序结果与 肇庆分离株同源性为100.0%，与国内外其他菌株同源性为99.0%－99.8%，说明ExhC 表皮脱落 毒素是该菌株的主要致病因子。该研究为广东省仔猪渗出性皮炎的病原学诊断、临床合理用 药及综合防控提供了参考数据。

关键词: 猪葡萄球菌；分离鉴定；表皮脱落毒素；药物敏感性试验